A belt buckle is known, for example, from U.S. Pat. No. 4,454,634 which includes a lock mechanism that is spring-loaded in the closing direction. The spring abutting on the lock mechanism is disposed such that when the belt tongue is not inserted, it spring-loads the belt tongue in the opening direction, and with an inserted belt tongue, it spring loads the belt tongue in the closed direction. Only one spring is thus required for the functionality of the lock mechanism. Due to the insertion of the belt tongue, the arrangement of the parts of the lock mechanism with respect to one another, and thus the orientation of the spring, is changed so that during the closing movement from the unlocking position into the locking position, the lock mechanism undergoes a changing spring loading that passes through a neutral position. In the locking position, a lock is held by a securing pin in engagement with the belt tongue. The securing pin is in turn guided in an L-shaped slotted guide system in a buckle housing. The ends of the securing pin are each always located in a recess formed in a frame of a pushbutton.
In a closing process the securing pin is moved in the recess in the frame, wherein after an automatic snap-closing of the lock after it passes through the neutral position, the spring of the securing pin abuts against the frame. To open the belt buckle, with an actuation of the pushbutton, the securing pin is moved from the frame of the button against the spring-load in the L-shaped slotted guide system. Via the lock mechanism, the spring is driven by the securing pin into its neutral position, whereupon an automatic opening of the belt buckle takes place.
When closing and opening of the belt buckle, the securing pin may strike against contact surfaces on the recess of the pushbutton due to the movement triggered by the spring after passing the neutral position, which causes undesirable noise.
In addition, it has been found that both in the locking and unlocking position, the securing pin can strike the contact region of the pushbutton, which generates additional noise.
Due to the increased requirements in modern motor vehicles with regard to acoustic behavior in the interior, it is desirable to reduce as much as possible the noise arising with locking and unlocking the belt buckle as well as during the drive.
The object of the present invention is therefore to at least partially solve the problems with respect to the prior art, and in particular to specify a belt buckle with which noise emission is reduced during locking and unlocking of the lock mechanism, as well as in the locking and unlocking position.